The new Foo Fighters album is “epic.” That’s the word from legendary rock producer Butch Vig, who shared the good news via his Twitter account. “We are officially done with the new Foo Fighters album. 23 straight days mixing! IT’S EPIC!!!” he tweeted on Wednesday.

It’s the first update from Vig since July 11. Then, as now, the recordings sounded “epic.” He wrote, “Just printed our first mix for the new Foo’s album! It sounds EPIC!”

Vig and Foo Fighters frontman Dave Grohl already have made history together on several occasions. Vig produced the great Nirvana album Nevermind from 1991 and worked on the Foo’s 2009 greatest hits and the 2011 set Wasting Light. He’s had a hand in many of the great rock records of the past 25 years, including albums released by Sonic Youth, Smashing Pumpkins, L7, House of Pain and his own project, Garbage.

The new Foo Fighters album is expected this fall. And with the as-yet-untitled effort, HBO will air a new series chronicling the “eight-city odyssey during which the record was created.” As previously reported, Grohl directed the series which visits studios in eight cities: Chicago, Austin, Nashville, Los Angeles, Seattle, New Orleans, New York and Washington, D.C. The veteran rockers recorded one song at each stop with local legends sitting in.